sc16is7xx: expose RTS inversion in RS-485 mode
sc16is7xx: expose RTS inversion in RS-485 mode

Hardware is capable of inverting RTS signal when working
in RS-485 mode.  Expose this functionality to user space.
Relay on a matching combination of standard flags
(SER_RS485_RTS_ON_SEND and SER_RS485_RTS_AFTER_SEND) to
detect when user space is requesting inverted RTS mode.

Signed-off-by: Jakub Kicinski <504f1c18b8f9ef3a97e2b56691879a48d8160f84@wp.pl>
Signed-off-by: Jon Ringle <475b225e077e06ce74799ac2e2339f6d9126b47c@gridpoint.com>
Signed-off-by: Greg Kroah-Hartman <4645f7897fd33786a2ee1264d590b3c400559d85@linuxfoundation.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs